In many radio communications systems, such as UMTS, mobile stations and user equipment are paged when there is an incoming call. Paging is commonly initiated from a controlling element of a radio access network, such as a radio network controller, RNC. Upon reception of a paging message, a User Equipment in idle mode enters connected mode to be able to respond to the page. When in idle mode, the User Equipment commonly communicates on a common channel. Also when in connected mode, when in some states such as URA_PCT, CELL_PCH or CELL_FACH, communications are commonly undertaken on common channels.
Within this patent application, a radio network controller, RNC, is understood as a network element including an RRM (Radio Resource Management) entity. The RNC is connected to a fixed network. Node B is a logical node responsible for radio transmission/reception in one or more cells to/from a User Equipment. A base station, BS, is a physical entity representing Node B.
With reference to FIG. 1, base stations <<BS 1>> and <<BS 2>> are physical entities representing Nodes B<<Node B 1>> and <<Node B 2>> respectively. <<Node B 1>> and <<Node B 2>> terminate the air interface, called Uu interface within UMTS, between UE and respective Node B towards the radio network controller <<RNC>>. <<RNC>> is connected to a fixed network <<Network>>.
In FIG. 1, the base stations are connected to the same radio network controller RNC. However, this specification also covers the exemplary situation where the base stations are connected to different RNCs. In UMTS, the RLC protocol is terminated in a serving RNC, SRNC, responsible for interconnecting the radio access network of UMTS to a core network <<Network>>.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Radio Link Control (RLC) protocol specification, 3GPP TS 25.304 v3.9.0, France, December 2001, describes UE procedures in idle mode and procedures for cell reselection in connected mode. Section 5.2 describes cell selection and reselection in idle mode. Subsections 5.2.6.1.4 and 5.2.6.1.5 specify cell reselection criteria and cell reselection parameters.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Radio Link Control (RLC) protocol specification, 3GPP TS 25.331 v3.9.0, France, December 2001, specifies radio resource control, RRC, protocol. Section 8.1.2 describes paging and section 8.3.1 describes cell and UTRAN registration area, URA, update procedures. Section 8.5.6 describes radio link failure criteria and actions upon radio link failure. Section 10.2.20 describes Paging Type 1, using PCCH (Paging Control Channel), and Paging Type 2, using DCCH (Dedicated Control Channel), messages for paging. Section 10.3.3.47 briefly describes U-RNTI (UTRAN Radio Network Temporary Identity) being allocated to a UE having an RRC connection and identifying the UE within UTRAN.
None of the cited documents above discloses a method and system for cell selection when entering connected mode from idle mode eliminating or reducing the risk of excessive transmission power and time for call setup.